The present invention relates to oxidation hair dyes and methods of dyeing hair using them.
Oxidative hair dye compositions in the form of creams have gained considerable importance in hair dyeing practice. Such hair dye compositions generally contain p-substituted benzene derivatives such as 2,5-diaminotoluene, 4-aminophenol 1,4-diaminobenzene, 2-(2'-hydroxyethyl)-1,4-diaminobenzene and 4-amino-N-(2'-mesylaminoethyl)aniline as well as 2,5-diaminoanisole, 2,5-diaminobenzyl alcohol, and tetraaminopyrimidine as oxidizing dyestuffs. The latter are known as developers. The developers are used in combination with suitable couplers. Such couplers include 1-naphthol, resorcinol, 4-chlororesorcinol, m-aminophenol, 5-amino-o-cresol and derivatives of m-phenylenediamine such as 2-amino-4-(2'-hydroxyethylamino)anisole. A wide assortment of different shades can be produced by a suitable combination of developers and couplers.
Oxidative hair dye compositions include two components which are mixed together shortly before use in a ratio of 1:1 and then applied to the hair to be dyed. One component, the dye carrier, contains the dye mixture and can take the form of a solution, gel or preferably a cream. The other component is usually in the form of a liquid or cream and contains a suitable oxidizing agent, e.g. hydrogen peroxide.
The dyeing takes place in the shaft of the hair by the reaction of the developers and couplers in the presence of an oxidizing agent.
In hair dyeing practice, highly-viscous dye carrier substances based on fatty alcohols are preferred when using mixtures of two components in the form of cream and in subsequent application with a brush. However, they have the disadvantage that they continue to thicken when stored so that it is considerably more difficult to remove them from the tube and mixing with the components containing the oxidizing ingredient requires more time. Moreover, conventional dye carrier substances in the form of cream tend to become "stringy" when removed from the tube, which makes handling more difficult.
The highly-viscous dye emulsion systems used in practice are very difficult to handle in technical production-related respects.
This is demonstrated during the production process, for example, in that the emulsion is first formed at relatively low temperatures so that the emulsion concentrates which can be diluted subsequently with cold water can be produced only with difficulty if at all.
An oxidizing hair dye composition in cream form having good stability when stored and a high dye/electrolyte content is known from the German Offenlegungsschrift or Published Patent Application 3 834 142, which concerns a low-viscosity preparation with a large number of ingredients. In addition to fatty alcohols and fatty acid esters, the composition contains a fatty acid monoethanolamide, lauryl alcohol ethoxylated with 2 moles ethylene oxide, and certain emulsifiers. Compositions of this type are preferably applied with the use of a shaker bottle. Accordingly, they cannot be applied by the users of the hair dye themselves. There is a risk with low-viscosity hair dye compositions that they can run off the hair because of reduced adherence to the hair.